The Monstera deliciosa, often called the Swiss Cheese Plant, has become a highly sought-after houseplant, especially as it matures into a large specimen with dramatic fenestrated leaves. For these substantial plants, proper watering stands out as the most important factor determining health and vigorous growth. The common question of “how much water” is misleading because the answer is not a fixed volume or a set schedule. Instead, successful watering depends entirely on assessing the current needs of the plant within its specific environment.
Determining When to Water
The greatest mistake a plant owner can make is watering a large Monstera on a strict calendar schedule, such as every seven or ten days. The time between watering sessions is highly variable and must be dictated by the condition of the potting mix, not by a date on a calendar. Potting mixes that contain a higher percentage of chunky materials like bark and perlite will dry out faster than those with a high peat content. Relying on an arbitrary schedule almost always leads to overwatering, which is the most frequent cause of Monstera decline.
The most reliable diagnostic tool for assessing moisture is the “finger test,” which requires physically checking the soil depth. For a large Monstera in a substantial pot, water should only be applied once the top two to three inches of the potting medium feel completely dry to the touch. Pushing a clean finger into the soil provides a direct, tactile assessment that is far more accurate than surface observation alone.
Some growers use electronic soil moisture meters, which can offer a numerical reading of the water content in the pot. While these tools can be helpful for checking the deeper parts of a large root ball, they are often prone to inaccurate readings due to mineral salts or poor calibration. It is best to use the meter in conjunction with the physical finger test for confirmation, especially when dealing with dense, large pots.
Another useful technique is the “lift test,” which involves judging the weight of the container. Immediately after a thorough watering, the pot will feel heavy due to the fully saturated soil and absorbed water. As the plant transpires and water evaporates, the pot gradually becomes noticeably lighter. The time to rewater is when the pot feels significantly lighter than its post-watering weight, indicating a substantial loss of moisture.
The Water Saturation Method
Once the soil assessment confirms the plant is ready for water, the focus shifts to ensuring the entire root system is properly hydrated. The correct technique involves a complete saturation of the root ball, often called the “drench and drain” method. Pouring a small amount of water repeatedly does not allow for even moisture distribution, leaving dry pockets within the dense soil mass.
To execute this, water should be applied slowly and evenly over the entire soil surface until it begins to flow freely out of the drainage holes at the bottom of the pot. This continuous flow indicates that the water has moved through all the potting medium, fully wetting the roots. The volume of water required to achieve this saturation will naturally be significantly greater for a large Monstera than for a small one.
It is necessary to allow all the excess water to drain away completely, which can take 15 to 20 minutes for a large container. Any water that collects in the drainage saucer must be discarded promptly after this period to prevent the roots from sitting in standing water. Leaving the roots submerged creates an anaerobic environment, which quickly leads to cellular damage and the onset of root rot.
How Size and Environment Affect Frequency
The frequency of watering, established by the soil dryness rule, is heavily modified by the physical size of the Monstera and the conditions of its surroundings. A larger plant possesses a greater leaf surface area and a more extensive root system. Although the soil in a larger pot may take longer to dry at the core, the sheer volume of water used by the plant causes the overall drying cycle to speed up.
The increased number of leaves results in a higher rate of transpiration, where water vapor is released through the stomata. This accelerated water loss means a large Monstera pulls moisture from the soil faster than a small plant, necessitating more frequent watering. The rate of transpiration is directly influenced by the intensity of the light the plant receives.
Monstera plants placed in bright, indirect light use water more quickly than those in lower light conditions. Higher light drives photosynthesis, which increases the rate of water vapor loss. Similarly, warmer room temperatures accelerate both evaporation from the soil and the plant’s transpiration rate, shortening the time between watering sessions.
Conversely, high ambient humidity slows down transpiration because the air is already saturated with moisture. This environmental factor extends the period between watering, as the plant conserves its internal water supply.
The container material also affects moisture retention. Porous, unglazed terracotta pots wick moisture away from the soil, leading to faster drying times. Non-porous plastic or glazed ceramic pots retain moisture much more effectively, keeping the soil damp for a longer duration. All these variables interact, making it impossible to establish a fixed schedule that works across different settings or seasons.
Recognizing Symptoms of Improper Watering
Even when following the best practices, a grower may need to troubleshoot based on the plant’s visual cues, which clearly signal if the current watering routine is incorrect. Recognizing the specific symptoms of under-hydration versus over-hydration is necessary for effective correction.
Underwatering manifests as a general wilting or drooping of the leaves, which appear limp and lack turgor pressure. If the soil has been dry for too long, the edges of the leaves may turn brown and become crispy, and the potting medium may visibly pull away from the sides of the container. This state requires immediate, thorough drenching to rehydrate the roots.
The symptoms of overwatering are often mistaken for underwatering but are overwhelmingly more common. The most telling sign is the yellowing of lower leaves, especially when the soil is still visibly moist, indicating a systemic problem. Overwatering causes root stress and suffocation because the lack of oxygen damages the cells responsible for absorbing water and nutrients.
Other signs of prolonged soil saturation include the appearance of black or brown spots on the leaves, soft or mushy stems near the soil line, and a persistent presence of fungus gnats. When these symptoms appear, the plant must be allowed to dry out significantly before the next watering, and the soil quality and drainage should be checked immediately.